The present invention relates generally to the assembly of a computer mass storage device having one or more data transducer access arms for positioning associated read and/or write heads proximate to selected data locations of one or more rotatable storage media. More particularly, the present invention relates to an apparatus, and an associated method, for laterally positioning a number of head/access arms relative to the individual planes of a stack of one or more rotatable storage media to permit contactless merging of the access arms and associated data transducers together with the storage media stack during assembly of a computer mass storage device head disk assembly ("HDA").
The positioning apparatus of the present invention laterally positions a head/access arm by applying forces to the access arm in a direction normal to a longitudinal axis thereof to displace the head access arm axially with respect to the plane of the associated disk. Because normal forces only are applied to laterally position the head/access arm with respect to the storage media, sliding contact between the positioning apparatus and the access arm is not encountered. As a consequence, contamination of the storage media caused by small, usually ferrous particles which might otherwise be generated as a result of sliding contact between a conventional positioning apparatus and the head/access arm is thereby avoided. Moreover, the positioning apparatus herein disclosed may be readily adapted to the manufacture of disk drives of ever smaller form factors and, when the disk drive incorporates a multiple number of storage disks concentrically arranged in a stack, the lateral positioning of individual ones of the head/access arms can also be individually adjusted medially between adjacent disks.
A magnetic disk drive is one type of computer mass storage device. Conventionally, a magnetic disk drive includes one or more rotatable magnetic disks or "platters". The magnetic disks contain a plurality of storage locations, generally arranged in concentric tracks, on which data may be stored. Conventionally, when the disk drive contains more than one magnetic disk, the magnetic disks are stacked in a vertical array and are mounted on a common axis or spindle of a spindle motor. During operation of the magnetic disk drive, the spindle motor is powered to cause a central hub together with the disk stack to rotate about the spindle.
The storage locations of the magnetic disks are accessed by a data transducer, commonly referred to as a read/write "head" which spans the rotating storage media disks. Data stored on the magnetic disks is encoded as bits of information comprising magnetic field reversals contained on the magnetically-hard surfaces of the magnetic disks. The head senses the magnetic fields of the storage locations and converts them into electrical signals to perform a "read" operation. At least one transducer is typically associated with each surface of a magnetic disk and, typically, a downhead transducer is positioned above each magnetic disk to access storage locations on an upper surface of the disk and an uphead transducer is positioned beneath each magnetic disk to access storage locations on a lower surface of the disk.
The heads are affixed at the distal end of an access arm which is attached at a proximal end to a positioner motor, usually a voice coil motor ("VCM"), which moves the access arm, together with the head, in an arcuate path across the surfaces of the magnetic disk. Conventionally, when the disk drive includes a plurality of access arms and associated heads associated with the individual disks in a stack, the access arms are all rigidly attached, or ganged, to a common positioner to move in unison.
When a plurality of storage media disks are mounted to a common spindle, the individual disks are spaced apart by small vertical separation distances to permit downhead and uphead transducers to access storage locations on the facing surfaces of adjacent ones of the disks. The vertical spacing between adjacent ones of the magnetic disks must therefore be great enough to permit the heads to access the storage locations of the respective disks. However, the individual disks must be located as closely together as possible in order to maximize the available storage capacity of the drive for any particular given form factor.
In normal operation, the heads do not physically contact the surfaces of the individual storage disks as such contact can either damage the head or unintentionally alter the values of the stored data. Contact between the head and the media can also permanently damage the disks rendering it impossible to read and/or write data to the affected area. Moreover, during assembly of the disk drive, the head transducers must initially be laterally positioned relative to the individual disks in the stack. Contact between the head, or the access arms which support the transducers, is possible during assembly of the disk drive if care is not exercised. To prevent damage to the magnetic disks during assembly of the disk drive, it is important to ensure that neither the head nor the access arm contact the surfaces of the magnetic disks.
Positioning of the head/access arm assemblies proximate to the magnetic disks during assembly of the disk drives is referred to as "merging" of the head/access arm assemblies together with the disks. Prior to merging, the head/access arm assemblies and the magnetic disks must be precisely positioned so that contact does not occur when the head/access arm assemblies are merged together with the disks.
As disk drives have and continue to become ever more miniaturized, even greater precision in the relative positioning of the head/access arm assemblies and the individual disks is required. As previously noted, with this increased miniaturization, the distance separating adjacent magnetic disks is reduced leaving less margin for error when laterally positioning the head/access arm assemblies relative to the disks. Current methods for merging the head/access arm assemblies with the disk stack involve applying small biasing forces to the access arms of the head/access arm assemblies. The biasing forces cause flexing of the access arms to alter their relative axial position with respect to the individual planes of the disks in the disk stack and this flexing of the access arms also alters the lateral positions of the individual heads suspended therefrom.
Such existing methods, however, may utilize positioning elements which engage the access arms and slide across their surfaces to effectuate the positioning operation. This sliding contact is not frictionless and abrasion between the positioning elements and the access arms may result. This abrasion can then generate particulate contamination which can settle upon the surfaces of the magnetic disks or otherwise contaminate the internal mechanism and electronics of the HDA. Inasmuch as the access arm and the positioning elements are usually formed of a ferrous-based alloy, any contamination of magnetic disks caused by such particles is particularly deleterious due to the potential for altering the magnetic properties of the disks.
Moreover, while conventional merging systems strive to minimize this sliding contact, a great deal of contamination can originate with the mechanism that moves the positioning elements themselves. Use of a cam, sliding shaft or wedge mechanisms all generate metal particles in close proximity to the disks and heads.
Means for laterally positioning the head/access arm assemblies relative to the magnetic disks of a disk drive which overcomes the problems associated with existing positioning methods apparatus would therefore be advantageous.
It is with respect to these considerations and other background information relative to computer mass storage media drives that the improvements of the present invention have evolved.